Are there “tricks” one can do with a multi meter to determine the ultimate breaker origin or load destination at the terminal strip? I’d rather not go through the process of disconnecting wires to see which loads aren’t working. The PO numbered the wires at the strip, but in most cases I have no idea the breaker of origin or the destination. Some suggestions would be appreciated.

Sure. There are lots of ways to do this.
One way is the hook the meter black lead to a good DC negative bus. Turn every breaker off. Then turn on one breaker (assuming you can turn it on and leave it on) and go down the terminal strip with the meter red lead looking for full battery voltage. When you find it, toggle the breaker to verify, then continue down the terminal strip. Write down what you find for you will not remember the details.
Repeat for the next breaker. It should only take a few minutes per breaker.

Something I've used to track wires from the bridge down to the engine room is a "cable sniffer". You connect a tone generator between the wire you are interested in and ground then go to the other end with the receiver and start poking around until you find the wire with the tone on it. The receiver works through insulation and the closer you get to the wire the louder it is.

We use a toner (like the one NWSeadog posted) a lot at work to trace wire runs on the older boats. Mine is a Fluke Pro3000, not overly expensive but seems to work better than others for longer wire runs. There are pretty cheap options available for just a one time use. If the KK42 wiring diagrams would help I think I got a set with our boat and could take pictures to send to you. Just let me know and I'll dig them out of storage.

Sure. There are lots of ways to do this.
One way is the hook the meter black lead to a good DC negative bus. Turn every breaker off. Then turn on one breaker (assuming you can turn it on and leave it on) and go down the terminal strip with the meter red lead looking for full battery voltage. When you find it, toggle the breaker to verify, then continue down the terminal strip. Write down what you find for you will not remember the details.
Repeat for the next breaker. It should only take a few minutes per breaker.

^^^^ This^^^
Simple, reliable. I have a Fluke toner, it works, but it's not foolproof. It was around $80, IIRC. The DC voltmeter/DMM is much more straightforward. Label all that you identify. You WILL forget!!

I had a 1978 F32 Trojan. I was able to order an owners manual from the Trojan website. It included a wiring diagram, original bill of sale and the usual owners info. It was awesome, unfortunately I can’t get anything like it for our President.

^^^^ This^^^
Simple, reliable. I have a Fluke toner, it works, but it's not foolproof. It was around $80, IIRC. The DC voltmeter/DMM is much more straightforward. Label all that you identify. You WILL forget!!

I assume you mean a Fox and Hound meter?

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